Automatic control system for granular material handling drums



May 11, 1954 B. 5. wow

AUTOMATIC CONTROL SYSTEM FOR GRANULAR MATERIAL HANDLING DRUMS 2 Sheets-Sheet 1 Filed Nov. 14, 1950 May 11, 1954 B. S. SNOW AUTOMATIC CONTROL SYSTEM FOR GRANULAR MATERIAL HANDLING DRUMS Filed Nov. 14, 1950 '2 Shets-Sheet 2 Patented May 11 1954 UNITED AUTOMATIC CONTROL SYSTEM FOR GRAN ULAR MATERIAL HANDLING DRUMS Barton S. Snow, Batavia, Ill., assignor to T. W.

Snow Construction Company, Inc., a corporation of Illinois Application November 14, 1950, Serial No. 195,616

15 Claims.

This invention relates to an apparatus for handling granular material by air pressure and more particularly to an automatic system for a pressure drum to intermittently deliver determined amounts of granular material to a pipelin by air pressure.

The primary object of this invention is to provide a fully automatic control system associated with a pressure drum which will not require manual operation.

Another object is to provide a control of the character described which will reduce scouring of equipment to a minimum.

A further object is the provision of a control of the character described which will automatically operate the drum to deliver a quantity of granular material as many times as that quantity is placed in the drum.

The invention is illustrated in exemplary embodiments in the accompanying drawings, in which:

Fig. 1 is a side elevation, partly [broken away and partly in section, of a sand drum and the control system embodying the invention; Fig. 2 is a view similar to Fig. 1 illustrating another embodiment of the invention.

The embodiments of the present invention will be described in connection with an installation suitabl for handling dry sand such as disclosed in my co-pending application Serial No. 125,908, filed November 7, 1949, now Patent No. 2,614,002 issued October 14, 1952. Thus, in the figures, sand may be placed in a receptacle 3 from which it is conveyed by gravity to a drum 4 adapted to hold approximately one ton. The sand is blown from the drum 4 by compressed air through a pipeline 5, either to a point of use or to a storage facility. Prior to this invention, a drum 4 has been used with manual controls resulting in waste of compressed air and also excessive scouring and pitting of the equipment, each time the operator failed to shut off the air supply reasonably soon after all the sand was blown from the drum. This invention contemplates replacing all prior manual operations with a completely automatic control system. The embodiments of Figs. 1 and 2 vary only in the particular structure or mechanism used to start the cycle operation, thus like reference numerals will be used in both figures.

In each of the figures thedrum is shown in condition to receive sand from the receptacle 3, the air supply from line 6 being shut off from the drum by the drum pressure control valve 1. The drum 4 is vented through a port the drum pressure control valve 1, to an exhaust 8 by means of a blowing line 9. Also in th condition shown, no air is present in the control system other than atmospheric air. A starting valve Ii) controls admission of air to the control system and is normally closed. The control system has an exhaust I I which is open in the condition illustrated in the figures of the drawings.

As the drum (Fig. 1) fills with sand, its weight exerts pressure on a bag l2 placed in the bottom of the drum 4. The bag is filled with a fluid which will not freeze and the interior of the bag is connected with the starting valve through a hydraulic line I3. The sand employed is generally dry and weighs approximately 100 pounds per cubic foot so that each vertical foot of sand exerts a pressure of approximately 0.69 pound per square inch on the bag l2. When the drum is full of sand, the pressure on the bag due to the weight of sand forces the fluid through line l3 into the top of the starting valve l0 and causes that valve to open, thus admitting air from the source 6 into the control system. Thus, air is lead through air motor supply line l4 to on side of an air piston motor l5 and up to a sequence valve [1. When the air in line l4 strikes the sequence valve ll, this valve closes and remains closed for a short period of time until the pressure within the valve on both sides of its gate is equalized. The sequence valve is available commercially. This time delay is suflicient to allow the pressure in line It to move the piston within the air motor l5 downwardly, with reference to the drawings, to shift a linkage is connected with the operating arm N3 of the drum pressure control valve 1. Upon this shift, the lever 19 of valve 7 is thrown to the dotted line position and connects an inlet port in the valve with blowing line 9 to allow air from the source 6 to enter through the high pressure supply line 2!! and blowing line 9 to the drum 4. Air is also admitted to portions 2! and 22 of the blowing line and to an air ram 23 through air ram line 25. The air ram closes valve 24 which previously admitted sand to the drum. Generally the air pressure used is between and pounds per square inch and the first puff of air admitted to the drum 4 will generally clear the valve seat of the valve 24 permitting a positive tight seal between the valve bOdy and the seat. The portion 22 of blowing line 9 leads to a blocking valve 26 which closes in response to the pressure built up within the drum. Valve 26 is generally closed in response to the drum pressure prior to the time that sequence valve i1 opens.

As thus far described, the drum is full of sand; air has been admitted to the drum to blow the sand into the pipeline 5; and a portion of the control system has been filled with compressed air from the source Compressed air now fills the air motor supply line which extends from starting valve ill to sequence valve ll; the high pressure supply line between source 5 and valve i and the blowing line from valve 7 to the drum and to the blocking valve 2%, plus line 25 to the air ram.

The drum is of a size to contain approximately 1 ton of sand which may be blown into the pipeline 5 in approximately 36 seconds, the air taking an additional seconds to permeate through the sand. Ii the air supply is of the pressure of ice pounds per square inch, the drum pressure while blowing the sand into the pipeline 5 will be substantially 160 pounds minus a small amount for friction loss and head loss in the piping. The loss in pressure, however, is small and may be disregarded in this application.

Also while the sand is being blown from the drum the starting valve ii: is held open and the air piston in the motor i5 is held in its lowermost position maintaining the drum pressure control valve '5 in position to admit air to the drum. The blocking valve 2t, being sensitive to the drum air pressure, remains closed to exclude compressed air from the remainder of the control system. A pressure gauge 5S provides visible indication of drum air pressure.

The condition described in the above para" graph remains until substantially all the sand is blown from the drum. The air pressure in the drum drops rapidly as the lower end of the pipe line 5 is cleared of sand, since the delivery end of the pipe is usually open. In using 100 pounds per square inch air supply, the pressure in the drum will generally drop to as low as pounds per square inch. This pressure drop afiects the pressure in blowing line portions 2i and 22 and is sufnciently low to allow the blocking valve 26 to open, permitting air from line ill to advance past the blocking valve to a second sequence valve (iii. This sequence valve is substantially the same as sequence valve ll and immediately closes upon air coming in contact with it. An air motor reversing line or branch line 3-5 is connected to a T 32 placed between the blocking valve 2&5 and sequence valve 3E3 and communicates with the lower end of the air piston motor l5.

An accumulator s2 is provided in the line 3! with a check-valve 33 positioned to admit air to the branch line it. The sequence valve til remains closed sufficiently long for the pressure to build up in the branch line 3% to a point approximately equal to the pressure of the air supply. A stopping valve 34, positioned between the air motor is and the starting valve ill in line it, is sensitive to the pressure in the branch line 31 by means of a connecting line 35. When the pressure builds up in the branch line, valve 3 closes in response to that pressure, shutting off further supply of air to parts of the system beyond the valve. At approximately this same time, sequence valve to opens and exhausts line M through the exhaust H. However, the pressure in branch line 36 remains because of the check valve 33 and reverses the position of the piston in the air motor 95. This moves the drum pressure control valve to connect line 9 leading to the drum 5 with the exhaust port 3, thus venting the drum l of any air pressure left therein. The air ram 23 is also relieved to atmospheric ill:

pressure permitting the valve 24 to open virtue of its own weight or by spring pressure desired.

This system and the condition described in the above paragraph is now substantially the same as that shown in the drawings and first described with the exception that air pressure remains in the branch line 3i A bleed 36 is set to exhaust the branch line St at a predetermined rate so that this line will be reduced to atmospheric pressure before the drum is again filled with J Of course, exhausting the branch line permits the stopping valve 34 to open and remain open until pressure is again built up in the branch line.

The embodiment of Fig. 2 is provided with the same system as that shown in Fig. l. The difference in these embodiments lies merely in the manner of operating the starting valve it to introduce air into the control system. In 2 the drum t is provided with a hopper ltil pivotally mounted on the top of the drum at till. Sand flows from receptacle 3 into the hopper and then by gravity through valve 24 into the drum. Sand backs up into the hopper its when the drum is full, and causes the hopper to tilt toward the dotted line position by reason of the weight of the sand alone. The hopper is constructed to have its center of gravity to the right of the pivot lili so that when filled with sand it will readily move to its dotted line position. A link system in connects the upper edge of the hopper with the plunger its of the starting valve it. Movement of the hopper opens the starting valve Ii! to admit air to the control system. The operations of the two embodiments shown are identical from the opening of the starting valve it. The air lines and valves are also the same.

While I have shown and described certain embodiments of my invention, it is to be under stood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may 'be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

1. An automatic control system for a lift drum used to deliver granular material to a pipe line by air pressure, comprising: a two position drum pressure control valve having an inlet port for admitting compressed air to the drum, and a vent port for venting the drum; a starting valve for admitting compressed air into said system; valve actuating mechanism connected to said drum to open said starting valve in respons to the amount of granular material contain said drum; an air motor connected to an air supply line in the control system for shifting the drum pressure control valve to open said inlet port after air pressure is admitted through said starting valve; a branch line in said control system for reversing said motor to return the drum pressure control valve to venting position and to shut off further air admission to the drum; and said system including automatic valves for outing off air from said branch line until a predetermined amount of the granular material has been delivered from the drum, said starting valve actuating mechanism holding the starting valve open until pressure in the drum is reduced.

2. An automatic control system for a lift drum used to deliver granular material to a pipe line by air pressure, comprising: a two position drum pressure control valve having an inlet port for admitting compressed air to the drum, and

a vent port for venting the drum; a starting valve for admitting air into said system; valve actuating mechanism connected to said drum to open said starting valve in response to the amount of granular material contained in said drum; an air motor connected to an air supply line in the control system for shifting the drum pressure control valve to open said inlet port; a branch line in said control system for reversing said motor to return the drum pressure control valve to venting position; a stopping valve in the air motor supply line, said stopping valve being controlled by the air pressure in the branch line; and said system including automatic valves for cutting off air from said branch line until a determined amount of the granular material has been delivered from the drum.

3. An automatic control system for a lift drum used to deliver granular material to a pipe line by air pressure, comprising: a two position drum pressure control valve having an inlet port for admitting compressed air to the drum, and a vent port for venting the drum; a starting valve for admitting air into said system; valve actuating mechanism connected to said drum to open said starting valve in response to the amount of granular material contained in said drum; an air motor connected to an air supply line in the control system for shifting the drum pressure control valve to open said inlet port; a branch line in said control system for reversing said motor to return the drum pressure control valve to venting position; and automatic valves in said system including a primary sequence valve, a blocking valve controlled by air pressure in the drum, and a secondary sequence valve, said valves being in series with the branch line being connected between the blocking valve and the secondary sequence valve, said valves cutting off air from said branch line until a predetermined amount of the granular material has been delivered from the drum.

4. A control system as specified in claim 1, in which the drum is provided with a port for admitting granular material, said port having a gate, and an air ram is provided to close said gate, said ram being operated by air from the control system admitted to the system through said drum pressure control valve.

5. An automatic control system for a lift drum used to deliver granular material to a pipe line by air pressure, comprising: a two position drum pressure control valve having an inlet port for admitting compressed air to the drum, and a vent port for venting the drum; a starting valve for admitting air into said system; a pressure respcnsive unit in the bottom of said drum having a connection with said starting valve to open said valve in response to pressure exerted on the unit by weight of material in the drum; an air motor connected to an air-supply line in the control system for shifting the drum pressure control valve to open said inlet port; a branch line in said control system for reversing said motor to return the drum pressure control valve to venting position; a check valve and a blocking valve in said branch line, said blocking valve being controlled by air in the drum; and said system including automatic valves for cutting off air from said branch line until a determined amount of the granular material has been delivered from the drum.

6. A control system as specified in claim 5, in which, a stopping valve is provided in the air-mo- 6 l tor supply line, said stopping valve being con trolled by the air pressure in the branch line.

7. A control system as specified in claim 5, in which, the drum is provided with a port for admitting granular material, said port having a gate, and an air ram is provided to close said gate, said ram being operated by air from the control system admitted to the system through said drum pressure control valve.

8. A control as specified in claim 5, in which, the air motor supply line is provided with an exhaust port, and the branch line is connected to the air-motor supply line, said branch line being provided with an air pressure accumulator and a check valve to retain pressure in said line after said exhaust port is vented to atmosphere, and a bleed nozzle to slowly reduce air pressure in the branch line to atmospheric.

9. An automatic control system for a lift drum used to deliver granular material to a pipe line by air pressure, comprising: a two position drum pressure control valve having an inlet port for admitting compressed air to the drum, and a vent port for venting the drum; a starting valve for admitting air into said system; a pivotally mounted hopper on the drum for directing material into the drum, and having a connection with said starting valve to open said valve when said hopper is tilted about its pivot by weight of material backed up into the hopper; an air motor connected to an air-supply line in the control system for shifting the drum pressure control valve to open said inlet port; a branch line in said control system for reversing said motor to return the drum pressure control valve to venting position; and said system including automatic valves for cutting off air from said branch line until a determined amount of the granular material has been delivered from the drum.

10. A control system as specified in claim 9, in which said automatic valves include a sequence valve and a blocking valve in series, said sequence valve being adapted to close upon admission of air to said system and to open after full pressure is built up in said system, and said blocking valve is controlled by air pressure in the drum.

11. A control system as specified in claim 9, in which, a stopping valve is provided in the air ,motor supply line, said stopping valve being controlled by air pressure in the branch line.

12. A control system for a lift drum used to deliver granular material to a pipe line by air pressure, comprising: a high pressure air supply line; a two position drum pressure control valve having an inlet port for admitting compressed air from said supply line through a blowing line to the drum, and a vent port for venting the drum; an air motor supply line connected to the high pressure air supply line; a starting valve for admitting air into said air motor supply line; valve actuating mechanism connected to said drum to open said starting valve in response to the amount of granular material contained in said drum; an air motor connected to said motor supply line for shifting the drum pressure control valve to open said inlet port; an air motor reversing line for reversing said motor to return the drum pressure control valve to venting position; and said system including automatic valves positioned between said air motor supply line and said air motor reversing line for cutting off air from said reversing line until a determined amount of granular material has been delivered from the drum, at least one of said automatic valves being responsive to air pressure in the drum to open and admit air to the motor reversing line upon lowering of drum air pressure to heiow blowing pressure.

13. A control system as specified in claim 12, in which the drum is provided with a port for admitting granular material, said port having a gate, an air ram is provided to close said gate, and an air ram line connects said ram with said blowing line.

14. A control system for a lift drum used to deliver granular material to a pipe line by air pressure, comprising: a high pressure air supply line; a two position drum pressure control valve having an inlet port for admitting compressed air from said supply line through a blowing line to the drum, and a vent port for venting the drum; an air motor supply line connected to the high pressure air supply line; a startingvalve for admitting air into said air motor supply line; Valve actuating mechanism connected to said drum to open said starting valve in response to the amount of granular material contained in said drum; an air motor connected to said motor supply line for shifting the drum pressure control valve to open said inlet port; an air motor reversing line for reversing said motor to return the drum pressure control valve to venting position; automatic valves positioned between said air motor supply line and said air motor reversing line including a primary sequence valve, a blockvalve controlled by air pressure in the drum, a secondary sequence valve, said air motor reversing line being connected to said air motor supply line between said blocking valve and said secondary sequence valve, said valves cutting ofi" air from said reversing line uti'l a predetermined amount of granular material has been delivered from the drum.

15. A control system for a lift drum used to deliver granular material to a pipe line by air pressure, comprising: a high pressure air supply line; a two position drum pressure control valve having an inlet port for admitting compressed air from said supply line through a blowing line to the drum, and a vent port for venting the drum; an air motor supply line connected to the high pressure air supply line; a starting valve for admitting air into said air motor supply line; valve actuating mechanism connected to said drum to open said starting valve in response to the amount of granular material contained in said drum; an air motor connected to said motor supply line for shifting the drum pressure control valve to open said inlet port; an air motor reversing line for reversing said motor to return the drum pressure control valve to venting position; a stopping valve in the air motor supply line being controlled by air pressure in said air motor reversing line; and said system including automatic valves positioned between said air motor supply line and said air motor reversing line for cutting ofi air from said reversing line until a determined amount of granular material has been delivered from the drum.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,858,561 Ruemelin May 1'7, 1932 1,991,932 Schaub Mar. 21, 1933 1,935,843 Goebels Nov. 21, 1933 2,932,367 Kennedy Mar. 3, 1936 2,221,741 Vogel-Jorgensen Nov. 12, 1940 2,389,651 Jeffery July 31, 1945 2,413,479 Wiegand Dec. 31, 19 16 FOREIGN PATENTS Number Country Date 180,397 Great Britain May 11, 1922 449,432 Great Britain June 26, 1936 

